147 research outputs found
Assessing signals of TMD physics in SIDIS azimuthal asymmetries and in the extraction of the Sivers function
New data on the Sivers azimuthal asymmetry measured in semi-inclusive
deep-inelastic scattering processes have recently been released by the COMPASS
Collaboration at CERN. Their increased precision and their particular binning,
in terms of as well as , motivates a new extraction of the Sivers
function, within the framework of a simple and transparent parametrization.
Signals of TMD effects visible in the Sivers asymmetries are critically
assessed. A thorough study of the uncertainties affecting the extracted Sivers
function is presented, including the low- and large- regions.Comment: 20 pages, 13 figure
Asymmetric collisions in MadGraph5_aMC@NLO
We will gain unprecedented, high-accuracy insights into the internal structure of the atomic nucleus thanks to lepton-hadron collision studies in the coming years at the Electron-Ion-Collider (EIC) in the United States. A good control of radiative corrections is necessary for the EIC to be fully exploited and to extract valuable information from various measurements. We present our extension of photoproduction at fixed order in MadGraph5_aMC@NLO, a widely used framework for (next-to-)leading order calculations at the Large Hadron Collider (LHC). It applies to electron-hadron collisions, in which the quasi-real photon comes from an electron as well as to proton-nucleus and nucleus-nucleus collisions
Simultaneous reweighting of Transverse Momentum Dependent distributions
The Bayesian reweighting procedure is extended to the case of multiple independent extractions of transverse
momentum dependent parton distributions (TMDs). By exploiting the data on transverse single spin asymmetries,
AN , for inclusive pion production in polarized proton-proton collisions measured at RHIC, we perform
a simultaneous reweighting of the quark Sivers, transversity and Collins TMD functions extracted from
semi-inclusive deep inelastic scattering (SIDIS) and e+e− annihilation into hadron pairs. The impact of the
implementation of the Soffer bound, as well as the differences between older and newer AN data, are
investigated. The agreement with AN data at large-xF values, a kinematical region complementary to those
explored in SIDIS measurements, is enhanced, improving the knowledge of the polarized quark TMDs in the
large-x region
Reweighting the Sivers function with jet data from STAR
The reweighting procedure that using Bayesian statistics incorporates the
information contained in a new data set, without the need of re-fitting, is
applied to the quark Sivers function extracted from Semi-Inclusive Deep
Inelastic Scattering (SIDIS) data. We exploit the recently published single
spin asymmetry data for the inclusive jet production in polarized
collisions from the STAR Collaboration at RHIC, which cover a much wider
region compared to SIDIS measurements. The reweighting method is extended to
the case of asymmetric errors and the results show a remarkable improvement of
the knowledge of the quark Sivers function.Comment: 9 pages, 5 figure
Reweighting the Sivers function with jet data from STAR
The reweighting procedure that using Bayesian statistics incorporates the information contained in a new data set, without the need of re-fitting, is applied to the quark Sivers function extracted from Semi-Inclusive Deep Inelastic Scattering (SIDIS) data. We exploit the recently published single spin asymmetry data for the inclusive jet production in polarized pp collisions from the STAR Collaboration at RHIC, which cover a much wider x region compared to SIDIS measurements. The reweighting method is extended to the case of asymmetric errors and the results show a remarkable improvement of the knowledge of the quark Sivers function
A Catalog of Coding Sequence Variations in Salivary Proteins’ Genes Occurring during Recent Human Evolution
Saliva houses over 2000 proteins and peptides with poorly clarified functions, including proline-rich proteins, statherin, P-B peptides, histatins, cystatins, and amylases. Their genes are poorly conserved across related species, reflecting an evolutionary adaptation. We searched the nucleotide substitutions fixed in these salivary proteins’ gene loci in modern humans compared with ancient hominins. We mapped 3472 sequence variants/nucleotide substitutions in coding, noncoding, and 5′-3′ untranslated regions. Despite most of the detected variations being within noncoding regions, the frequency of coding variations was far higher than the general rate found throughout the genome. Among the various missense substitutions, specific substitutions detected in PRB1 and PRB2 genes were responsible for the introduction/abrogation of consensus sequences recognized by convertase enzymes that cleave the protein precursors. Overall, these changes that occurred during the recent human evolution might have generated novel functional features and/or different expression ratios among the various components of the salivary proteome. This may have influenced the homeostasis of the oral cavity environment, possibly conditioning the eating habits of modern humans. However, fixed nucleotide changes in modern humans represented only 7.3% of all the substitutions reported in this study, and no signs of evolutionary pressure or adaptative introgression from archaic hominins were found on the tested genes
Inhibition of pluripotency networks by the Rb tumor suppressor restricts reprogramming and tumorigenesis
Mutations in the retinoblastoma tumor suppressor gene Rb are involved in many forms of human cancer. In this study, we investigated the early consequences of inactivating Rb in the context of cellular reprogramming. We found that Rb inactivation promotes the reprogramming of differentiated cells to a pluripotent state. Unexpectedly, this effect is cell cycle independent, and instead reflects direct binding of Rb to pluripotency genes, including Sox2 and Oct4, which leads to a repressed chromatin state. More broadly, this regulation of pluripotency networks and Sox2 in particular is critical for the initiation of tumors upon loss of Rb in mice. These studies therefore identify Rb as a global transcriptional repressor of pluripotency networks, providing a molecular basis for previous reports about its involvement in cell fate pliability, and implicate misregulation of pluripotency factors such as Sox2 in tumorigenesis related to loss of Rb function
Inhibition of pluripotency networks by the Rb tumor suppressor restricts reprogramming and tumorigenesis
Mutations in the retinoblastoma tumor suppressor gene Rb are involved in many forms of human cancer. In this study, we investigated the early consequences of inactivating Rb in the context of cellular reprogramming. We found that Rb inactivation promotes the reprogramming of differentiated cells to a pluripotent state. Unexpectedly, this effect is cell cycle independent, and instead reflects direct binding of Rb to pluripotency genes, including Sox2 and Oct4, which leads to a repressed chromatin state. More broadly, this regulation of pluripotency networks and Sox2 in particular is critical for the initiation of tumors upon loss of Rb in mice. These studies therefore identify Rb as a global transcriptional repressor of pluripotency networks, providing a molecular basis for previous reports about its involvement in cell fate pliability, and implicate misregulation of pluripotency factors such as Sox2 in tumorigenesis related to loss of Rb function
Supersymmetric Nonlinear O(3) Sigma Model on the Lattice
A supersymmetric extension of the nonlinear O(3) sigma model in two spacetime
dimensions is investigated by means of Monte Carlo simulations. We argue that
it is impossible to construct a lattice action that implements both the O(3)
symmetry as well as at least one supersymmetry exactly at finite lattice
spacing. It is shown by explicit calculations that previously proposed
discretizations fail to reproduce the exact symmetries of the target manifold
in the continuum limit. We provide an alternative lattice action with exact
O(3) symmetry and compare two approaches based on different derivative
operators. Using the nonlocal SLAC derivative for the quenched model on
moderately sized lattices we extract the value {\sigma}(2, u_0) = 1.2604(13)
for the step scaling function at u_0 = 1.0595, to be compared with the exact
value 1.261210. For the supersymmetric model with SLAC derivative the discrete
chiral symmetry is maintained but we encounter strong sign fluctuations,
rendering large lattice simulations ineffective. By applying the Wilson
prescription, supersymmetry and chiral symmetry are broken explicitly at finite
lattice spacing, though there is clear evidence that both are restored in the
continuum limit by fine tuning of a single mass parameter.Comment: 35 pages, 36 figures, 2 tables; updated version as accepted by JHE
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